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By David Freeman
Dragons may be a make-believe, but a dragon-shaped aurora borealis that flickered in the sky over Iceland this month was breathtakingly real – just have a look at this dramatic photo.
The photo taken by Jingyi Zhang on Feb. 6, became NASA's astronomy photo of the day on Feb. 18 and has been widely viewed online since. It shows a swirling green aurora over a dark, snowy landscape where the solitary figure – the photographer's mother – stares up at the sky as if awestruck.
An aurora borealis forms when fast-moving charged particles from the sun strike Earth's magnetic field, colliding with oxygen and nitrogen atoms and molecules in Earth's upper atmosphere, exciting them and causing them to release particles of light known as photons.
Because these collisions are focused on the Earth's magnetic field at the North and South Poles, they are commonly seen in the high north and south latitudes. In the Northern Hemisphere, they are known as aurora borealis or the northern lights; in the Southern Hemisphere, they are called aurora australis or the southern lights.
Auroras tend to be green, like the dragon-shaped one, but they can also be shades of red, blue, violet, pink and white. They're too faint to be seen in daylight. At night, some are pretty dim but others are bright enough to read by.
And while auroras can be beautiful, the so-called solar storms that trigger them can disturb radio transmissions on Earth and satellite operations in space. "So the solar storms can benefit the auroras … but hurt some kinds of long-distance communications," Jay Pasachoff, an astronomer at Williams College in Williamstown, Massachusetts, said in an email.
Auroras have also been observed on other planets, including Jupiter and Saturn.
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